2009; Pope and Dockery, 2006; Pope et al., 2009). Considerable published research documents our understanding of indoor–outdoor relationships of important air pollutants, including particles and ozone (Jia et al., 2008b; Monn, 2001; Wallace, 1996; Weschler et al., 2000). Research has explored the extent to which health risks associated with outdoor pollutants are a consequence of indoor exposures (Weschler, 2006; Wilson and Suh, 1997; Wilson et al., 2000). A large body of work reports on how indoor pollution sources influence IAQ and human health (Jones, 1999; Samet et al., 1987, 1988), including a National Research Council report published three decades ago (NRC, 1981).

The following sections discuss how indoor air pollutant levels might be influenced by climate change. The discussion is organized according to pollutant source category and pollutant class, considering first indoor emission sources and second pollutants of outdoor origin. The treatment is not intended to be comprehensive, but rather broadly illustrative of important IAQ concerns that might be influenced by climate change. Although most of what follows is related to conditions in buildings of the types commonly found in the United States, the chapter concludes with a discussion of an important international public-health problem: exposure to smoke from the indoor combustion of solid biomass and coal in developing countries.

Indoor environments detain pollutants that are emitted indoors. This section reviews important IAQ issues that are associated with indoor pollutant sources and explores how climate change might affect these issues. The emphasis is on conditions in the United States but the discussion is relevant for other countries with similar levels of economic development and similar buildings.

Pollutants from Indoor Combustion

Pollutants released into indoor air cause roughly 100–1,000 times greater human inhalation exposure or dose per unit mass emitted than pollutants released into outdoor air (Smith, 1988). That important observation has been expressed in terms of “intake fraction” (Bennett et al., 2002; Nazaroff, 2008), the ratio of the mass of a pollutant inhaled by an exposed population to the mass of the pollutant emitted from a source. The significance of that point in the present context is that sources have a much larger effect on public health if their pollutants are emitted indoors rather than outdoors. The much higher intake fraction for indoor emissions compared to those outdoors leads to the understanding that small-scale combustion

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